John Calvin Commentary Numbers 10:31

"And he said, Leave us not, I pray thee; forasmuch as thou knowest how we are to encamp in the wilderness, and thou shalt be to us instead of eyes." — Numbers 10:31 (ASV)

And he said, Leave us not, I pray thee. Moses perseveres and urges what he had just said: that Hobab should be a sharer in the prosperity which God had given His people reason to expect.

“To this end” (he says) “thou hast known all our stations in the desert.” Commentators do not appear to have observed or understood these words, for they translate them simply as, “for thou hast known,” as if Moses desired to retain Hobab to be of use to himself. However, there is more than one causal particle here;¹⁰ thus, it is literally, “Since, for this cause, thou hast known all our resting-places,” etc.

Its meaning, then, is as follows: Hobab was ill-advised for his own interest because he had borne many inconveniences for this reason—that he might at some time or other receive his recompense. It is as if Moses were saying, “Why have you until now endured so many inconveniences while directing our course, unless it was so that you might enjoy with us the blessings of our repose?”

In a word, Moses signifies that Hobab's labors would be vain and fruitless unless he endured them a little while longer, until, together with the children of Israel, he could enjoy the promised inheritance.

What is said here, then, does not relate to the future, as if Moses had said, “Be to us instead of eyes, as you have been previously.” Instead, by reminding him that the reward for his labors was at hand, Moses urges and encourages him to proceed.

¹⁰ כי על-כן. Translated in . Translated in A. V., Genesis 18:5, , for therefore; Judges 6:22,, for because; Jeremiah 38:4,, for thus; and here,and here, forasmuch as.